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Raspberry Pi Official 7'' Touchscreen Display

adema87

hi i bought this display from MELOPERO on 7 December 2024 to mount it on a raspberry pi5 8gb with ubuntu server 24 lts with desktop installed. i have only one problem and it is the backlight management. even with the raspberry turned off the backlight stays on, when the system is in standby it stays on, it always stays on! i contacted the official ubuntu support who helped me several times but doesn't know what to do. can you help me?

  • 0

    Do you have any extra electrical devices plugged into the system? For instance, I have a pair of active speakers and a HDMI switch to automatically select between a PVR and an old STB, depending on which device I am watching and/or recording. Sometimes when I switch it all off, the STB is audible through the speakers, very quiet, but still audible, even though I was watching the PVR at the time. I suspect crossover between the inputs on the HDMI switch but havn't had time to sort it out for a while. One thing I do know though is that one of the HDMI leads is not connecting properly, a quick wiggle of the lead usually gets it working again, but it is a newish lead, such things should not happen.

    One or more of the power-on LEDs will stay on for about half a minute too. This is a bit worrying; it could mean that I have a couple of PSU's fighting each other via the HDMI boxes to see who can provide the highest 5 volts. You may have a similar situation with your back-light. Some LED's can still emit light at quite low voltages, they don't change colour as the voltage slowly disappears like a filament bulb would - white down to yellow, then red, then off. An LED can take 30 seconds or more depending on the PSU(s) and you don't see them fade, they just stop when the stored energy runs out.

    Does your system feature seperate PSU's for the back-light and the Pi, or are they both powered by the same PSU? Your problem sounds like a leak of some sort, but I admit it could take some finding! Does the backlight flicker at all if you jiggle the power leads a bit? That's all I can think of for now, so good luck.

  • 0 in reply to electronicbiker

    hi, same psu, the original raspberry one. unfortunately I also think of residual current in the circuit and probably the same that powers the red shutdown LED. a real nuisance because from vpn server it must always remain on but with the display off and it comes by itself that the backlight will always remain on. I'm waiting for official assistance and then you will have to try with a resistance in the middle as for the LEDs in cars.....reading around the use of these displays leads to a thousand problems, firmware versions, backlights, strange resolutions......